The use of lamps of the above variety as heat sources is known. For example, extensive use has been made of tungsten halogen lamps (those containing a halogen within the envelope as part of the atmosphere thereof) by the reprographic industry, particularly in photocopy machines of the direct electrostatic type. Tungsten halogen lamps provide the basic advantages of fast warm-up, compact size and high energy loading, high color temperature and constant lumen maintenance. Lamps of this type have also been successfully utilized in such heating requirements as annealing, brazing, curing of protective coatings, and the drying of paints and adhesives. As indicated, such lamps have proven to be excellent heat sources for supplying relatively instant, concentrated radiant heat. This is due, primarily, to the fact that approximately seventy percent of the radiant energy emitted by these lamps is infrared.
When used in a typical photocoy machine, such a heat producing lamp is also referred to as a fusing lamp and is particularly designed to "set" the toner utilized by the machine.
Lamps of the above type typically include, in addition to the aforementioned tubular envelope, a base member on each end of the envelope. Examples of such bases are illustrated in U.S. Pat. Nos. 3,001,096 (Mosby); 3,001,097 (Smialek); 3,274,426 (Scoledge et al); and 4,442,374 (Morris et al). As described therein, the bases for these lamps typically are of relatively small construction (relative to the envelope) and are positioned on a relatively small portion of the envelope's press-sealed end portions. Such bases may be of a ceramic or similar material (i.e., as in U.S. Pat. No. 3,001,096) and provide connection to the lamp's external lead wire through some form of conductive cap (or contact) secured to the base.
Lamps of the above variety have typically possessed one or more of the following disadvantages: (1) poor electrical connection between the lamp and the respective power source (these lamps typically being positioned within a connector or socket which in turn is coupled to the source); (2) the need for relatively expensive connectors or sockets needed to accommodate the lamp; and (3) failure to adequately protect the seal area (at the envelope's ends) against breakage during handling and during operation (insertion and/or removal). The last mentioned disadvantage is particularly significant when considering the relatively delicate nature of lamps of the infrared type which include the aforementioned elongated, tubular glass envelope which, in some examples, may reach approximately forty inches in length and have an outer diameter of only about 0.375 inch.
It is believed, therefore, that an electric lamp which overcomes the several disadvantages mentioned above would constitute a significant advancement in the art. It is further believed that a lamp possessing such capability and which can be produced in both a relatively inexpensive and facile manner would constitute an even further advancement in the art.